This invention relates to a method of creating an interface between a node and a local exchange of a digital telecommunications system, and to apparatus for preparing instructions for the creation of such an interface. The invention is particularly applicable to the creation of a V5.2 interface between an Access Node (AN) and a local exchange of an SDH telecommunications system.
The node of a telecommunications system is programmed with node manager software which enables the node to be configured and maintained. During the installation of the node, that software is also used to create an interface between the node and its local exchange of the telecommunications system in response to a set of instructions which will include various parameters input by an engineer installing the interface.
In general, the manager software will be able to warn the engineer if any of the parameters have been incorrectly set. However, correcting the parameters can be a time-consuming and confusing process since some of the parameters are interrelated such that the correction of one parameter can have a bearing on the requirements of the other parameters.
According to the invention, there is provided a method of creating an interface between a node and a local exchange of a digital telecommunications system to enable a number of different types of telecommunications traffic to pass along a plurality of channels from one to the other of the node and the local exchange over signal link means, the method comprising performing, in sequence, the steps of:
(a) allocating identification data to the signal means to enable the local exchange to determine the identity of the node;
(b) specifying which of the channels are to be transmitted along the signal link means; and
(c) for each specified channel, specifying the type of telecommunications traffic to be carried thereby.
This particular sequence of steps facilitates the creation of an interface since any important errors in or omissions from the information provided at each step can be rectified before the subsequent steps occur and without affecting the information (if any) provided for the previous steps.
The steps of the method can be performed by inputting appropriate data into a suitable data processing device, for example a lap top computer, which then transmits the data to the node as a set of instructions for the latter to set up the interface.
Preferably, the steps of the method constitute the preparation of instructions for the setting up of the interface, the method comprising the further step of subsequently implementing the instructions. It will be appreciated that the sequence of steps involved in the implementation of the instructions need not necessarily be the same as the sequence of steps involved in preparing the instructions.
Preferably, the signal link means comprises a plurality of data links, for example cables, physically connecting the node to the local exchange. In this case, a respective identification is preferably allocated to each link.
Preferably, the interface allows various overhead signals for the telecommunications traffic to pass from one to the other of the node and local exchange.
The telecommunications traffic can be arranged in a succession of frames having time slots for channels for the overhead signals, in which case steps (b) and (c) are preferably performed by specifying along which link each of those channels is to be conveyed, and for each channel, the nature of the overhead signal to be carried thereby.
Preferably, step (c) also involves specifying which of said channels is to carry vital signals for maintaining said interface. The method preferably also includes the step of checking whether a channel for said signals has been allocated, and preventing the implementation of the instructions until such an allocation has been made. Thus, the risk of setting up an interface with no channel for vital control signals is avoided.
The method preferably includes the further step of ensuring that, before the instructions are implemented, a back up channel, for carrying the vital control signals in the event of the failure of the first said channel for those signals has been allocated.
The local exchange may be connected to each of a plurality of nodes via a respective interface created by this method, the method therefore including the additional step of allocating a respective identification to the interface.
Preferably, that additional step is the first step of the method.
Preferably, the interface is a V5.2 interface.
The invention also lies in data processing apparatus for preparing instructions for the creation of an interface bet ween a node and the local exchange of a digital telecommunications system, the apparatus comprising data input means for enabling the apparatus to receive the data necessary to prepare the instructions, and signal output means for supplying a signal, which contains said instructions, to the system, wherein the apparatus is so arranged as to require the following data for the instructions to be input into the apparatus in the following sequence:
a) data identifying signal link means via which the node and local exchange are to communicate with each other;
b) data specifying the communications channels to be transmitted over the signal link means; and
c) for each such channel, data specifying the type of telecommunications traffic to be carried thereby.